000
FXUS61 KCTP 140549
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
1249 AM EST Wed Feb 14 2018
.SYNOPSIS...
High pressure will drift east and off the New England coast
tonight. An increasingly moist southerly flow will bring
unsettled conditions from mid week until a cold front passes
through Friday ushering drier conditions for the weekend.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Near term forecast problem remains centered on the potential
for some light icing overnight into early Wednesday morning.
The favorable right entrance region of an upper jet streak and
increasing warm advection/isentropic lift will bring a small
chance of some very light rain/drizzle/freezing drizzle. The
latest radar shows some light disorganized showers moving
through WRN PA. With surface temps hanging close to freezing,
we will issue an SPS to cover potential for icy pockets. If it
becomes apparent precip is actually hitting the ground as it
moves into the CWA, we may need a short lived advisory.
From earlier...
The HRRR shows a small area of very light precip streak across
the area from I-80 northward after midnight. The SPC HREF keeps
the area dry so the confidence in actually seeing precip is
pretty low.
Covered the low threat and spotty nature of any light icing in
the Hazardous Weather Outlook for now. If confidence increases
that some light precipitation will actually develop, we will
have to issue a short lived headline for slippery travel.
Min temps overnight will be in the 25-30 deg range. The wind
will be mainly east to southeast at 5-10 mph.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
Better chances for rain arrive late in the day or early evening
Wed with upper level diffluence increasing and mid-lvl winds
into the 50s out of the West.
Max temps Wednesday will be about 10F warmer than Tuesday and it
will be mild enough for plain rain everywhere by then.
Rainfall amounts will stay rather light and generally several
hundredths to around 0.10 of an inch, as the forcing continues
to look disorganized.
Temps will be very mild with well above normal mins and maxes
Wed night and Thursday. So, despite the cloudiness on Thursday,
the temps should rise into the 50s and some 60s across the
south. 70F might not be all that far south of the Mason-Dixon
line.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Temperatures will be on the rise for the second half of the
week, along with the opportunity for rain. The springlike surge
of mild air should send temperatures 20+ degrees above average
Thursday and Thursday night. The mild weather will be erased
(briefly) as a cold front sends temperatures falling on Friday
before readings bottom near normals levels for mid February on
Saturday. High temperatures on Saturday will be 20 to 30 degrees
colder than Thursday (48-hour change).
As high pressure migrates off the Eastern Seaboard, broad
ascent in the warm air advection pattern will allow for clouds
and periods of light rain, drizzle and fog to develop Wednesday
night and Thursday. Model guidance continues to advertise the
potential for enhanced rainfall Thursday night into Friday in
response to strengthening southwesterly low level jet along a
tightening baroclinic zone/frontal boundary pushing southeast
from the Midwest/OH Valley. Ensemble PWAT values reach +3SD
above normal. The anomalous moisture combined with cold
ground/enhanced runoff could lead to heavy rainfall (1-2+
inches) and flooding potential. At this time, the greatest risk
area is focused from southern OH into northern WV and southwest
PA including the Laurel Highlands. The placement of the high
QPF axis is still uncertain and the Day 3 WPC excessive rain
risk area splits the difference between the southern GFS and
northern ECMWF precip axis.
An ECMWF/CMC/GEFS consensus brings the possibility of some
wintry weather back into the picture later Saturday into
Saturday night. Will need to see if this recent model trends
hold and the GFS comes on-board before increasing confidence
and sensible wx elements. But it is something to definitely
monitor in the coming days. Sunday looks dry for now with
precipitation returning into early next week. After a short
break, the mild trend should resume next week with above average
temperatures a good bet.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...

-- Changed Discussion --

East...west band of rain and sleet across central PA as of
Midnight.
06Z TAFS sent.
Earlier discussion below.
MVFR has spread through the western TAF sites as southwesterly
upper level flow couples with moist southerly flow at the
surface. Expect this flow to continue as the night continues.
Cigs and vsbys will continue to degrade as the night continues
and through the daybreak. However latest HRRR keeps pushing back
IFR cigs and vsbys further back in time. Considering the dry
lower atmosphere, this should hold true so have removed IFR
tonight. Brief periods of IFR are still possible at JST from 10Z
to 13Z, however not likely so have left it off.
Light rain showers continue to stream through the northern half
of PA overnight tonight, however only MVFR vsbys are expected
from these. There is a low probability for some patchy little
mixed precipitation (mainly light freezing rain or freezing
drizzle) late. For now...left this out of the TAF fcsts... given
how dry the low levels are and anticipated spottiness with
little organized upper dynamics to generate appreciable swaths
of precipitation.
Outlook...
Wed-Thu...Low cigs/light rain possible, mainly N Mtns (KBFD).
Fri...Windy and turning much colder. AM rain, changing to
periods of light snow or snow showers mainly across the Western
Mtns. Cig reductions likely early, and continuing during the
afternoon across the NW mtns and Laurel Highlands.
Sat...No sig wx expected.
Sat night and Sunday...Chance of snow and lowering Cigs/Vsbys
to MVFR with areas of IFR.